ENABLE CHEAT CONSOLE:

1. First you must activate the Developers Console: you do this at the main menu, select Options, then Keyboard/Mouse. Enable Allow Developers Console.
2. While playing the game on any difficulty level, press the tilde key (which looks like ~ on your keyboard) to display the console window. After you enable the cheat console, type Sv_Cheats 1? and then press ENTER. This will enable the cheat mode. After that enter the following codes and hit ENTER to activate them. Now go directly to the cheat codes list below.
3. On the Steam control panel, Right Click with your mouse on the Left 4 Dead 2 option, and select Properties under the My Games tab. In the General tab, select Set Launch Options, enter -console in that field, and accept it. Start the game, and the console window should appear. Enter bind p toggleconsole as a console command. Close the console window, and start a single player game. While playing the game, press P to display the console window, then enter sv_cheats 1 and press ENTER to enable cheat mode. Look at the bottom for a list of map names. * (If the message Cant use cheats now; please exit to main menu and start your own server with map mapname so that you can enable cheats. appears, enable the map c5m1_waterfront or map c5m2_park code. You will return to the main menu. Enable either map code again, then enable the sv_cheats 1 code again.